Introduction
Invasive coronary angiography (CA) is the traditional imaging modality for evaluation
of the coronaries and guidance of percutaneous coronary intervention (PCI) during
treatment of ST-segment elevation myocardial infarction (STEMI) [1]. However, CA provides
just a two-dimensional luminography of the coronaries, without additional insights
into plaque morphology, extent of atherosclerosis, thrombus burden and mechanisms
of vessel occlusion [2].
The use of optical coherence tomography (OCT) delivers high-resolution images that
accurately depict vessel and lesion characteristics, including the presence of thrombus,
provides incremental assistance in stent implantation and minimizes stent-related
issues [2]. OCT may also reveal the pathophysiology of arterial thrombosis, and optimize
therapeutic options during PCI, especially in young patients where mechanisms of STEMI
may vary [3].
Though plaque rupture remains the most common etiology of myocardial infarction (MI),
in patients younger than 40–45 years unique syndromes such as plaque erosion, coronary
microvascular dysfunction, spontaneous coronary artery dissection (SCAD), myocarditis,
coronary embolism, hypercoagulable state and coronary spasm (drug related or not)
are prevalent [3]. Consequently, intracoronary imaging is essential to clarify the
underlying mechanisms when treating young MI patients, since stenting might not be
the holy grail in this subgroup. Thrombus aspiration, though not routinely advocated
by the guidelines, is required in selected patients for the recovery of coronary flow
during primary PCI [1]. Previous reports have highlighted that in selected young patients
presenting with STEMI, lone thrombus aspiration without balloon angioplasty or stenting
is feasible and is associated with favorable short and long-term outcomes [4]. Dedicated
thrombectomy catheters have been developed, but one size does not fit all anatomies,
with some catheters being too small to accommodate a large thrombotic burden [5].
Aim
We report the case of a young patient who presented with anterior STEMI and underwent
thrombectomy of a large free-floating thrombus through a “home-made” aspiration device,
assembled from a guiding extension catheter and a guide catheter. OCT showed no signs
of plaque rupture, allowing deferral of stent implantation.
Case report
A 38-year-old man, with positive family history for coronary artery disease, presented
with acute chest pain. Electrocardiography revealed hyperacute T waves in leads I,
aVL, V2- > V6, corresponding with the diagnosis of an anterolateral STEMI (Figure
1 A). He was loaded with 250 mg of aspirin, 180 mg of ticagrelor and underwent emergency
CA, via the right radial artery approach. CA revealed a subtotal occlusion of the
proximal segment of the left anterior descending artery (LAD) with the presence of
a mobile thrombus (Figure 1 B arrow) whereas the left main stem, circumflex and right
coronary artery were normal. In view of the free-floating thrombus in the proximal
segment of the LAD we decided to proceed with thrombus aspiration. After administration
of 7500 IU of unfractionated heparin via a 6-French 3.5 extra back-up (EBU, Medtronic)
guiding catheter, we tried to perform thrombosuction through a standard 6-French aspiration
catheter, without success. We hypothesized that the small inner diameter (1.1 mm)
of the standard aspiration catheter (Medtronic, Export) was not large enough to aspirate
the large thrombus burden accumulated in the LAD.
Figure 1
A – ECG showing anterolateral STEMI. B – Angiography revealed the presence of thrombus
(arrow) in the proximal LAD. C – Guide extension catheter (arrow) through the guiding
catheter at the proximal LAD
Taking into consideration the large diameter of the vessel at the lesion site (between
3.5 and 4.00 mm), the proximal location of the thrombus and the large thrombus burden,
we decided to construct a wider diameter “home-made” aspiration device by using a
6-French guiding extension catheter, which has an inner diameter of 1.45 mm and would
theoretically offer a greater aspiration potential. Specifically, a 6-French Guidezilla
II guide extension catheter (Boston Scientific) was advanced through the EBU guiding
catheter at the proximal LAD (Figure 1 C, arrow). Successful thrombectomy was performed
through the “guide extension-guiding catheter” assembly via a 20 cc luer-lock vacuum
aspiration syringe attached to the manifold by a three-way stopcock (Figure 2 A).
Prior to any further manipulation, vigorous back-bleeding through the Y-connector
was performed, to eliminate any chance of air or thrombus embolism. Intracoronary
injection of tirofiban followed, to ensure adequate resolution of thrombus microparticles,
resulting in an excellent angiographic result (Figures 2 B, C). OCT illustrated normal
lumen area with presence of minimal thrombus remnants (Figures 2 D, E, arrow), intima
thickening and fibroatheroma (Figure 2 D, asterisk) without any signs of plaque rupture
at the lesion site, allowing deferral of stent implantation. Control CA after 3 days
revealed a perfect result.
Figure 2
A – Guide extension-guiding catheter assembly: arrows indicate the luer-lock syringe
attached to manifold, guidewire and guide extension catheter. B, C – Perfect angiographic
result after thrombus aspiration. D, E – OCT illustrating presence of minimal thrombus
remnants (D, E arrow), intima thickening and fibroatheroma (D, asterisk) without any
signs of plaque rupture
The patient was discharged in good condition with lifelong aspirin and ticagrelor
for 1 year. At 3-month follow-up he was asymptomatic with a normal echocardiogram.
Further investigation excluded paradoxical emboli but revealed a positive lupus anticoagulant,
for which rheumatologists advised lifelong use of aspirin.
Discussion
Restoring coronary blood flow is of utmost importance in the treatment of STEMI during
primary PCI. Impaired flow and decreased coronary perfusion is related to reperfusion
injury, causing arrhythmias, suboptimal microvascular circulation, contractile abnormalities,
permanent myocardial dysfunction and fatal events [6, 7]. Thrombus aspiration has
been proposed as an adjunct to primary PCI to further improve epicardial and myocardial
perfusion by the prevention of distal embolization of thrombotic material and plaque
debris [1]. Despite the fact that thrombus aspiration can improve coronary blood flow
and resolve ST-segment elevation, it is not routinely advocated by the guidelines
(Class IIIA) [1].
The two landmark TASTE and TOTAL trials, which investigated the role of routine manual
thrombus aspiration versus conventional PCI, showed no benefit in clinical outcomes
of routine aspiration overall or in the high thrombotic risk subgroup [8–10]. Additionally,
increased risk of stroke was noted in the TOTAL trial [9, 10]. Similarly, in a meta-analysis
of 17 trials, aspiration thrombectomy was not shown to be of benefit in reducing the
risk of death or reinfarction [11]. In the high-thrombus burden subgroup, the trend
towards reduced cardiovascular death and increased stroke/transient ischemic attack
(TIA) calls for further research and use of improved thrombus aspiration technologies
in this high-risk subgroup [12].
However, in patients with heavy thrombotic burden, thrombus aspiration should be considered.
Several randomized trials have demonstrated the effectiveness and safety of manual
thrombus aspiration during primary PCI. The majority of studies in the literature
conclude that thrombectomy improves TIMI flow and provides rapid resolution of ST
segment deviation. The TAPAS and EXPIRA trials, along with a few meta-analyses, reported
that thrombectomy improves the long-term clinical outcome of reducing cardiac death
and major adverse cardiovascular events (MACE). However, these studies showed no statistical
significance for the prediction of MACE [13, 14]. The EXPIRA trial illustrated a reduction
of the infarct area in cardiac magnetic resonance imaging, after thrombectomy [14].
A survival benefit among patients with STEMI was suggested by the TAPAS trial [13].
In addition, STEMI is an uncommon entity in young adults and its incidence depends
on the cut-off age used [15]. Most studies have used an age cut-off of 40–45 years
to define young patients with STEMI [3]. It has been reported that < 1% of patients
with STEMI are ≤ 35 years [15]. Young STEMI patients differ from older patients in
the risk factor profile and in the extent of atheromatic plaque coronary burden. In
particular, young coronary patients are characterized by a higher proportion of heavy
smoking, a lower proportion of hypertension and diabetes mellitus and a relatively
high proportion (15–20%) of angiographically “normal” coronary arteries [15]. Apart
from the classical mechanism of plaque rupture, MI in young individuals can be attributed
to plaque erosion, coronary microvascular dysfunction, SCAD, myocarditis, coronary
embolism, hypercoagulable state and coronary spasm related or not to drug use (e.g.
cocaine) [3]. In particular, the presence of antiphospholipid antibodies, such as
the positive lupus anticoagulant detected in our patient, is a known risk factor for
arterial and vein thrombosis by causing a hypercoagulable state [3]. Therefore, diverse
underlying mechanisms may be present in young patients with MI, requiring tailored
interventional and drug therapy. The use of OCT is essential to reveal the underlying
pathophysiology, and optimize therapeutic options [2]. In our patient OCT showed no
signs of plaque rupture, allowing deferral of stent implantation after adequate thrombus
aspiration.
From a practical point of view, coronary diameter varies between individuals, and
commercially available thrombectomy catheters may not be suitable for certain anatomies
to achieve sufficient thrombus aspiration (Table I A). Guiding extension catheters
have a larger inner diameter and can offer a greater aspiration potential (Table I
B). The assembly and use of a home-made aspiration catheter has already been described
above. Of note, this technique should only be used if the coronary artery is large
enough to accommodate the assembly, since the guide extension catheter can dissect
the coronaries and only when the guiding catheter has perfectly engaged the coronary
artery to avoid dislocation of thrombus to the systematic circulation during manipulations.
Table I
Characteristics of commonly used thrombus aspiration (A) and guide extension catheters
(B)
A. Thrombus aspiration catheters (size 6 Fr)
Manufacturer
Device trade name
Catheter length [cm]
Aspiration lumen area/diameter [mm2/mm]
Vascular Solutions
Pronto V3
140
0.93/1.09
Medtronic
Export AP
140
1.08/1.17
Diver CE
145
1.01/1.14
Boston Scientific
Fetch 2
135
0.79/1.00
Terumo
Eliminate
140
0.79/1.00
Priority One
140
0.85/1.04
Merit Medical
ASAP AC Kit
140
1.24/1.26
Meril
Aspiron
140
0.69/0.94
Stentys
Stentys AC
145
0.95/1.10
B. Guide extension catheters (size 6 Fr)
Boston Scientific
Guidezilla
145
1.65/1.45
Guidezilla II
150
1.65/1.45
Vascular Solutions
GuideLiner
150
1.58/1.42
IMDS
Guidion
150
1.58/1.42
Boosting Catheter
QX Medical
150
1.65/1.45
Teleflex
Trapliner
150
1.58/1.42
Conclusions
Diverse underlying mechanisms may be present in young patients with MI, requiring
a case-by-case approach. The use of intracoronary imaging is essential to elucidate
the diagnosis and optimize therapeutic options. In selected young patients with MI,
OCT-guided lone thrombus aspiration without balloon angioplasty or stenting, either
by conventional means or home-made aspiration catheters, can be a feasible and effective
therapeutic approach.